Dietary fiber refers to the part of plant-based foods that is not digested. Fiber passes through the digestive tract providing no vitamins, or minerals, or nutrients. In spite of its seeming lack of contribution to our wellbeing, fiber is absolutely essential for maintaining good health. As undigested fiber passes through our intestines, it affects how other nutrients and chemicals are absorbed. Soluble fiber can lower cholesterol, reduce rates of certain cancers, prevent diverticulitis, slow the absorption of sugar and reduce insulin spikes, and speed transit time through intestines, preventing constipation. Fiber intake has been a topic of concern over the past few years, because chronic illnesses associated with low fiber are on the rise, even as consumption of foods rich in fiber is decreasing. The Institute of Medicine recommends a daily intake of 20 -30 grams of fiber. Most Americans do not consume half that amount.

Researchers at the Center for Community Health and Health Equity at Brigham and Women’s Hospital, Boston, MA recently completed an examination of long-term trends in dietary fiber in American adults. Dr. Cheryl Clark and her colleagues analyzed data from 23,168 men and nonpregnant women gathered by the National Health and Nutrition Examination Survey from 1999-2010. Their analysis focused on associations between dietary fiber intake and cardiometabolic risks including metabolic syndrome, cardiovascular inflammation, and obesity.

Their analysis of the NHANES, published in The American Journal of Medicine, found that among different racial and ethnic groups in the U.S., Mexican Americans (18.8 grams) consumed more fiber than either non-Hispanic whites (16.3 grams), or non-Hispanic blacks (13.1 grams). In addition, the researchers found that “the consumption of dietary fiber was consistently below the recommended total adequate intake levels across survey years. Our study also confirms persistent differences in dietary fiber intake among sex, socioeconomic status, and racial/ethnic subpopulations over time. On average, young males consumed almost 20 g less dietary fiber than recommended amounts, with particularly low consumption by young non-Hispanic black men. Older women had dietary fiber intakes that were closest to, yet still an average of 6 g below, recommended amounts of fiber for their age group. Importantly, lower dietary fiber intake was associated with a higher prevalence of cardiometabolic risks among American adults.”

Conversely the analysis found that increased consumption of dietary fiber “was associated with lower levels of inflammation within each racial and ethnic group, although statistically significant associations between dietary fiber and either obesity or metabolic syndrome were seen only among whites.” The team concluded that “associations between higher dietary fiber and a lower prevalence of cardiometabolic risks suggest the need to develop new strategies and policies to increase dietary fiber intake.”